Continuously operable plant for degassing and pouring metal melts

ABSTRACT

Degassing and pouring of metal melts has hitherto generally been carried out as a batch process, due to the necessity of removal of the vacuum during recharging of the melt-feeding means, e.g. crucible. Plant has not been devised which allows the degassing and pouring operation to be carried out continuously, in that the melt-feeding means, i.e. crucible or feed head, is connected to a vacuum chamber by a transfer passage, and in that the vacuum head consists of an electromagnetic conveyor trough to convey the melt to the pouring lip within the vacuum.

United States Patent Friedrich Schnake Rheinhausen, Germany 783,990

Dec. 16, 1968 Oct. 5, 1971 AEG Elotherm Gmbll Remscheid-Hasten, Germany Feb. 15, 1968 Germany Inventor Appl. No. Filed Patented Assignee Priority CONTINUOUSLY OPERABLE PLANT FOR DEG ASSING AND POURING METAL MELTS 4 Claims, 2 Drawing Figs.

US. Cl 266/34 V,

Int.Cl C2lc 7/10 Field of Search 266/34, 34 A, 34 V; 75/49; 164/63, 257

References Cited UNITED STATES PATENTS 9/1936 Betterton et a1.

2,140,607 12/1938 Thompson 266/34 2,734,240 2/1956 Southern 266/34 3,212,767 10/1965 Muller 266/34 3,310,850 3/1967 Armbruster 75/49 FOREIGN PATENTS 1,198,071 8/1965 Germany... 266/34 Primary Examiner-Gerald A. Dost Attorney-Cushman, Darby & Cushman ABSTRACT: Degassing and pouring ofmetal melts has hitherto generally been carried out as a batch process, due to the necessity of removal of the vacuum during recharging of the melt-feeding means, e.g. crucible.

Plant has not been devised which allows the degassing and pouring operation to be carried out continuously, in that the melt-feeding means, i.e. crucible or feed head, is connected to a vacuum chamber by a transfer passage, and in that the vacuum head consists of an electromagnetic conveyor trough to convey the melt to the pouring lip within the vacuum.

PATENTED BET 5 I971 mwwe/ 2 III'III II w Z l I SHEET 2 OF 2 INVENTOR MMAMWW ATTORNEYS CONTINUOUSLY OPERABLE PLANT FOR DEGASSING AND POURING METAL MEL'I'S This invention relates to a continuously operable vacuum plant for degassing and pouring metal melts.

For improving the physical properties of metals a wellknown procedure consists of melting them in a vacuum and in drawing off the volatile substances that are driven out of the melting metal. For performing this method the solid metal is first placed into a crucible inside a vacuum chamber and then melted, preferably by induction heating. When all the solid metal in the crucible has been melted down, it is degassed by evacuation of the vacuum chamber and then poured into ladles or the like.

It is also known to melt a metal from the solid state under atmospheric pressure in a crucible and then to pour the molten metal into a second crucible inside a vacuum chamber in which it is degassed under vacuum and then poured. However, these procedures have the defect that degassing and pouring of the metal melt cannot proceed in a continuous process because each time the liquid metal is poured after having been degassed in the vacuum, the melting furnace that has been discharged in the vacuum chamber must be recharged with solid metal and the fresh metal melted, or, alternatively, each time it has been emptied the crucible in the vacuum chamber must be taken out and refilled with molten metal.

It is the object of the present invention to provide vacuum plant for degassing and pouring molten metals in continuous process. For achieving this object the invention proposes to provide the crucible for the reception of the liquid melt with a transfer passage for delivering the liquid metal into an electromagnetic conveyor trough of which the lip is connected to a pouring spout, and to provide the pouring spout as well as the conveyor trough with a vacuum tight cover to fonn the vacuum chamber.

FIG. 1 shows a first embodiment of a continuously operable degassing and casting plant according to the invention, and

FIG. 2 shows a second embodiment of a continuously operable degassing and casting plant according to the invention.

The same reference numerals indicate the same elements throughout.

An embodiment of the proposed vacuum plant is shown in longitudinal section in FIG. 1 of the accompanying drawings, wherein 1 is a crucible which is filled with a metal melt 2. The crucible wall 3, which consists of a brick lining 4 and a metal casing 5, is provided near the bottom with a transfer passage 6 which directly delivers the molten metal into an electromagnetic conveyor trough 7. The lip 8 at the end of the conveyor trough 7 is connected to a pouring spout 9 which may be provided with a closure 10 for pouring the liquid metal when required. The pouring spout 9 as well as the conveyor trough 7 including the lip 8 are surrounded by a vacuumtight cover 11 which thus forms a vacuum chamber 12 for degassing the molten metal. For conveying the molten metal 2 through the conveyor trough 7 into the pouring spout 9 an inductor 13, preferably a three-phase inductor, is attached to the floorplate 14 of the conveyor trough 7 and connected to the electrical I mains.

As the metal melt 2 which has already been molten, preferably in an induction furnace, enters the crucible 1, it also flows through the transfer passage 6 into the vacuum chamber 12 which between the ascending part of the conveyor trough and the lining 15 of the cover 11 it fills to a level that differs from that in the crucible 1 because of the vacuum pressure maintained in the vacuum chamber 12. When sufficient liquid metal 2 has been filled into the crucible for the metal surface in the crucible 1 and in the vacuum chamber 12 to have risen beyond the top of the transfer passage 6, voltage is applied from the three phases of the main not shown to the inductor 13. The electromagnetic forces acting on the melt 2 operate to convey the melt up the conveyor trough 7, lifting it over the lip 8 into the closed pouring spout 9 which is thus filled. At the same time as the inductor 13 is energized, the air in the vacuum chamber 12 is evacuated by a vacuum pump, not shown, generating a vacuum pressure inside the vacuum chamber 12 which causes the liquid metal to be degassed by the removal therefrom of volatile constituents, and the quality of the melt thereby to be improved. When the melt 2has been degassed, the sliding gate 10 which serves as a closure in the pouring spout 9, is opened and the degassed melt 2 can be teemed for instance into chill moulds, casting moulds or the like. During the teeming of the degassed melt from the pouring spout 9 the melt 2 which is yet to be degassed in the vacuum chamber 12 is conveyed up the conveyor trough into the pouring spout 9 at a rate which depends upon the adjustable voltage applied to the inductor. According to the quantity of metal that is poured the surface of the bath falls, both in the conveyor trough portion 7 and in the crucible 1. However, in order to maintain continuity in the process of degassing the melt 2 and of pouring the same, that is to say in order to carry out the degassing and pouring processes continuously without interruption the crucible 1 is refilled! with molten metal as soon as the metal melt 2 which it contains has fallen to a minimum level directly above the top of the transfer passage 6. In place of a crucible 1 for the reception of the metal melt 2 a feedhead l6 and a downgate 17 leading to the bottom of the vacuum chamber 12 as shown in FIG. 2 might be used. How ever, if this is done it is advisable to make good the unavoidable temperature loss which occurs during the introduction of the metal melt from the induction funnace into the feedhead 16, by surrounding the downgate 17 with a cylindrical induc tion coil or trough-shaped inductor 18 for reheating the melt 2.

What is claimed is:

l. A continuously operable vacuum plant for degassing and pouring metal melts, comprising a crucible for the reception of the metal melt, a vacuum chamber and a transfer passage which joins the bottom of said crucible to the bottom of said vacuum chamber, for transferring metal melt from said crucible to said vacuum chamber, said vacuum chamber including a pouring spout, an open, upwardly inclined electromagnetic conveyor trough with an inductor arranged under the full length thereof, said conveyor trough communicating at its lowermost end with said crucible and having a lip at its uppermost end connected to said pouring spout, a vacuumtight cover surrounding said electromagnetic conveyor trough and pouring spout and means for providing a vacuum withinsaid vacuumtight cover said crucible, said transfer passage and said vacuum chamber having such dimensions that when said vacuum-producing means is operating and said inductor is not operating a level of metal melt is drawn into said vacuum chamber through said transfer passage which is lower than the upper end of said electromagnetic conveyor trough so that when said inductor is energized, said metal melt is conveyed to the upper end of said conveyor trough solelyunder the influence of the electromagnetic field, is subjected to the vacuum within said vacuumtight cover which removes impurities from said metal melt and pours out from said vacuum chamber through said pouring spout.

2. A continuously operable vacuum plant for degassing and pouring metal melts, comprising a feed head, a downgate from said feed head, a vacuum chamber and a transfer passage which joins the bottom of said downgate to the bottom of said vacuum chamber, for transferring metal melt from said downgate to said vacuum chamber, said vacuum chamber including a pouring spout, an open, upwardly inclined electromagnetic conveyor trough with an inductor arranged under the full length thereof, said conveyor trough communicating at its lowermost end with said crucible and having a lip at its uppermost end connected to said pouring spout, a vacuumtight cover surrounding said electromagnetic conveyor trough and pouring spout and means for providing a vacuum within said vacuumtight cover said feed head and downgate, said transfer passage and said vacuum chamber having such dimensions that when said vacuumproducing means is operating and said inductor is not operating a level of metal melt is 3. A vacuum plant according to claim 2, in which the said downgate is surrounded by an induction coil for reheating the metal melt.

4. A vacuum plant according to claim 2, in which the said downgate is surrounded by a trough-shaped inductor for re- I heating the metal melt. 

2. A continuously operable vacuum plant for degassing and pouring metal melts, comprising a feed head, a downgate from said feed head, a vacuum chamber and a transfer passage which joins the bottom of said downgate to the bottom of said vacuum chamber, for transferring metal melt from said downgate to said vacuum chamber, said vacuum chamber including a pouring spout, an open, upwardly inclined electromagnetic conveyor trough with an inductor arranged under the full length thereof, said conveyor trough communicating at its lowermost end with said crucible and having a lip at its uppermost end connected to said pouring spout, a vacuumtight cover surrounding said electromagnetic conveyor trough and pouring spout and means for providing a vacuum within said vacuumtight cover said feed head and downgate, said transfer passage and said vacuum chamber having such dimensions that when said vacuumproducing means is operating and said inductor is not operating a level of metal melt is drawn into said vacuum chamber through said transfer passage which is lower than the upper end of said electromagnetic conveyor trough so that when said inductor is energized, said metal melt is conveyed to the upper end of said conveyor trough solely under the influence of the electromagnetic field, is subjected to the vacuum within said vacuumtight cover which removes impurities from said metal melt and pours out from said vacuum chamber through said pouring spout.
 3. A vacuum plant according to claim 2, in which the said downgate is surrounded by an induction coil for reheating the metal melt.
 4. A vacuum plant according to claim 2, in which the said downgate is surrounded by a trough-shaped inductor for reheating the metal melt. 